Preservation of rubber



Patented Jan. 17, 1939 I Ira Williams, Woodstown, N. J and ArthurMorrill Neal, Wilmington, Del., assignors to E. I.

du Pont de Nemours & Company, Wilmington, Del., a corporation ofDelaware UNITED STAT No Drawing. Application December 24, 1935,

a Serial No. 56,086

14 Claims. (CI. 18-50) This invention relates to the preservation ofcompounds of this class, when incorporated in rubber and moreparticularlylto rubber. having rubber by any of these methods, give tothe ru incorporated therein compounds which retard ber greatly increasedage-resisting properties. that deterioration which is due to the actionof In order to illustrate the advantageous features heat and oxygen. ofthese compounds rubber stocks were mixed It is well known that rubber inuse is frequently according to the following formula: Parts subjected tothe action of heat and of oxygen, Pale crepe 100 as a result of whichthe rubber rapidly de- Zinc T ",T 100 teriorates. It has, heretofore,been proposed to sulfur 3 add Substances to rubber in order to give the'gg 1 rubber a longer life and to retard deterioration. Lithopone 20Among the many different classes of oom- Diortho g g ifig aiflg 075pounds which have been proposed for this purpose Deterioration inhibitorprobably the most important have been the sece ondary aryl amines, suchas phenyl beta naphthylamine. These compounds have proved to besatisfactory when incorporated into a rubber mix 7 before vulcanizationbut are not well adapted for use in latex.

An object of this invention-is to provide a new These stocks were curedunder steam pressure to a comparable state of cure and were then aged inan oxygen bomb for '72 hours at C. under an oxygen pressure of 300pounds per square inch, with the results indicated in the followingtable.

class of compounds which will increase the age- Deterimmninhibim t e fig in resisting properties of rubber. A further object None 2950Completely is to provide a class of compounds which may be wdeteriorated easily prepared in aqueous emulsion form for 2875 after 48$5 treating vulcanized and unvulcanized latex. Still 3375 2400 furtherobjects are to provide a new composition of matter and to advance theart. Other objects 22 2 00 will appear hereinafter. v

These objects are accomplished by the following invention whichcomprisesincorporating with rubber a compound having the formula:

Other compounds in this class which deserve special mention are: themethyl, propyl, and higher aliphatic derivatives of both the alpha H andbeta 'naphthylamines, and unsaturated de- R-N'A in which R represents anaphthyl nucleus which may be substituted and A is an alkyl or alkarylgroup. f

The term alkyl, as used throughout the specification and claims,' is tobe understood'lto include the unsaturated as well as saturated'aliphatic radicals. V

The term alkaryl, as used throughout the specification and claims, is tobe understood to mean saturated or unsaturated aliphatic radicals joineddirectly to the nitrogen and having an aryl, radical substituted for ahydrogen of the aliphatic V radical. I H

i In general the compounds of this class are liquids and will form anemulsion with water; Due to this characteristic, of this class ofcompounds,'they are particularly adapted for use in treating vulcanizedand unvulcanized latex by adding the compounds thereto in the form of anaqueous emulsion. They may also be used in treating Vulcanized rubber byany of the commonly employed methodslof impregnation, The

such as crotyl alpha naphthylamine and vinyl beta naphthylamine. Stillother compounds which may be mentioned are:

Beta-phenyl-ethyl-beta-naphthylamine A h I r e ;r..

--CH CH3 p-Methyl-benzyl-alphamaphthylamine I v 17 1 -orn-onr [n-pom'rivatives of both alpha and beta naphthylamines,

r 1 HxCWNmCHz-O 7-111ethyl-2-benzyl amino-naphthaleneBeta-hydroxy-p-methyl-benzyl-alpha-naphthylamine7-amino-2-ethylaminc-naphthalene Allyl a=naphthylamine7-methoxy-Z-allyl-amino-naphthalene CH=CH2 Vinyl a-naphthylamine5-methy1-1-crotyl-amino-naphthalene Nil) CHzCH=CHz7-amino-2-a1lyl-amino-naphthalene V H V @NCH=CH2 I V6-ethoxy-Z-vinylamino-naphthalen:

While we have illustrated the effect of these compounds as incorporatedinto a rubber mix which is thereafter vulcanized, it is understood thatthey are substantially equally effective when employed as an aqueousemulsion in the treatment of vulcanized and unvulcanized latex and whenapplied to vulcanized rubber by any of the well known methods 'ofimpregnation.

We have disclosed the use of one part of a sub stance of this class to100 parts of rubber, however, it is to be understood that theseproportions may be widely varied according tothe desire of themanufacturer, without departing from the spirit of our invention. .Weprefer to employ 1 from about 0.5 to '5 parts of 'inhibitorto 100 partsof rubber as being the most eifective, in general practice.

This is in part a continuation of our copending application, Serial No.596,572, filed March 3, 1932, for Preservation of rubber.

While we have disclosed certain specific compounds of the class andcertain methods of employing the same, it is to be understood that manyvariations and modifications will appear to those skilled in the artwithout departing from the spirit of our invention. Accordingly thescope of our invention is to be limited solely by the appended claimsconsidered as broadly as is permissible in view of the prior art.

We claim:

1. The method of preserving rubber which comprises incorporating thereina compound having the formula wherein R represents a naphthyl nucleusand A represents a member of the group consisting of allyl, crotyl andvinyl.

2. Rubber having incorporated therein a compound having therformula i RNA V wherein R represents a naphthyl nucleus and A represents a memberof the group consisting of allyl, crotyl and vinyl. I r

3. The method of preserving rubber which comprises incorporating thereinallyl-beta-naphthyl- RI1IA wherein R represents a naphthyl nucleus and Arepresents a member of. the group consisting of allyl, crotyl and vinyl.

10. The method of preserving rubber in latex which comprisesincorporating in the latex an aqueous emulsion of a' compound having theformula R'ILTA wherein R represents a hydrocarbon radical of thenaphthalene series and A represents an unsaturated aliphatic hydrocarbonof the group consisting of allyl, crotyl and vinyl.

11. The method of preserving rubber in latex which comprisesincorporatingin the latex an aqueous emulsion ofallyl-beta-naphthylamine.

12. Latex obtained by the method of claim 9. 13.'Latex obtained by themethod of claim 10. 14. Latex obtained by the'method of claim 11.

.IRA WILLIAMS. g

ARTHUR MORRILL NEAL.

